Timing selector for cameras having electronic timers

ABSTRACT

A timing setter for cameras having an electronic timing circuit containing an RC member which includes a stepped rheostat and a mechanically movable setter for setting the time constant, wherein the timing setter 10 contains at least two arms 11, 12 which up to a certain transitional range come successively into engagement with the contacts 4, 5 and 6 of the stepped rheostat with possible bridging over of successive contacts, each sliding arm 11, 12 being electrically connected respectively with an associated capacitor 20, 21, the two capacitors being sufficiently different in size so that when the arms are in the transitional range the time constant of one arm is approximately the same as that of the other arm, while the two capacitors are uncoupled from each other.

United States Patent TIMING SELECTOR FOR CAMERAS HAVING ELECTRONICTIMERS 8 Claims, 3 Drawing Figs.

US. Cl 95/53.3, 95/53 Int. Cl G031) 9/58, 60% 9/64 Field of Search95/53.3, 53

References Cited I Primary Examiner--Samuel S. Matthews AssistantExaminer-Robert P. Greiner AttorneyKrafit and Wells ABSTRACT: A timingsetter for cameras having an electronic timing circuit containing an RCmember which includes a stepped rheostat and a mechanically movablesetter for setting the time constant, wherein the timing setter 10contains at least two arms 11, 12 which up to a certain transitionalrange come successively into engagement with the contacts 4, 5 and 6 ofthe stepped rheostat with possible bridging over of successive contacts,each sliding arm 11, 12 being electrically connected respectively withan associated capacitor 20, 21, the two capacitors being sufficientlydifferent in size so that when the anus are in the transitional rangethe time constant of one arm is approximately the same as that of theother arm, while the two capacitors are uncoupled from each other.

PATENTEDJUN man 3,583,302

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ATTORNEYS PATENTEUJUN 8H)?! 3.583302 sum 2 or 2 Fig.2 /3 15 /47/5 12 17000 4 "/NvENToRs Pefer Laser/es Ar'fhur' Kass/er ATTORNEYS TIMINGSELECTOR FOR CAMERAS HAVING ELECTRONIC TIMERS BACKGROUND OF THEINVENTION The field of the invention is photography, particularlycameras having shutters with a delayed releaser.

The invention relates to a timing selector for cameras with electronictimers consisting of an RC member comprising a stepped rheostat with amechanically movable contact member for setting the time constants. Anexample of this prior art timing selector is disclosed in West Germanprinted Specification 1,263,492 of Franz Starp, which issued Mar. 14,1968.

Another apparatus for electronic exposure control in photographiccameras is disclosed in British Patent 1,086,300, of Reimann et al.,which issued Oct. 4, 1967. According to the disclosure of Reimann et al.there are two timing cycles cooperating with one another. These are usedin the case of self portraits, etc. The exposure time switching systemis set in operation after the expiration of the delayed action time.

SUMMARY OF THE INVENTION The object of this invention is to provide atiming selector with a large timing range which is operative directlywith the 8" camera setting and having any desired length of closuretime.

The problem of increasing the timing range is solved in the presentinvention by providing a movable contact member with at least twocontact arms which are brought successively into engagement with thecontacts up to a transitional region so as to bridge over any possiblegaps by having each contact arm come into electric connection with anassociated capacitor of such a size that the time constant of onecontact arm for the transitional region is about the same as the timeconstant for the other contact arm, and so that the capacitors will bedisconnected from one another.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more readilycomprehended by reference to the accompanying drawings, wherein:

FIG. 1 is a schematic representation of the circuit of the timingselector;

FIG. 2 shows in section a particular modification of the mechanicalconstruction of this timing selector; and

FIG. 3 shows a section on the line Ill-III of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic timer is bestexplained by reference to FIG. I, wherein a battery 1 is connected by aswitch 34 to a stepped rheostat 2 consisting of separate resistors 3 andcontacts 4, 5 and 6. The stepped rheostat 2 is arranged along an arcwhose inner angle is smaller than 180 C. A rotatable setter carries twoswitch arms 11 and 12 which form a conductive path between contacts 4, 5and 6 and contact paths 13 and 14. In their intermediate positions theends of the switch arms bridge over the gaps between neighboringcontacts. The contacts do not permit any open circuits so that a motorconnection is possible with the rotatable setter in any angularposition.

Contact path 13 is electrically connected to a capacitor 20 and contactpath 14 to a capacitor 21. The electric charge which at times appears atcapacitor 20 or 21 is conducted by a discharge circuit to a terminal 22which serves as the input for an electronic control circuit for shutteractuation. The discharge circuit is shown in the drawing as consistingof two diodes 23 and 24 but can consist of transistors or otherrectifying elements. Parallel to the stepped rheostat 2 there is anelectrically connected resistor 30, in series with a contact 31 adjacenta sliding point 32 which is electrically connected by a switch 33 withthe capacitor 20. The switches 33 and 34 are controlled by adisconnecting key (not shown) so that when the disconnecting key isdepressed, the switch 33 will first be opened and then the switch 34closed, whereas when the key is released first the switch 33 will beclosed and then the switch 34 opened.

The sliding arms 11 and 12 of the rotatable setter 10 are fixed inrelation to one another and subtend an angle a, which is slightlysmaller than the central angle 04,. When the sliding arm 11 arrives uponone of the last contacts 6 of the stepped rheostat 2, then the slidingarm 12 arrives at the first contact 4 of the series. As can be seen fromFIG. 1, the sliding track 13 is slightly longer than the sliding track14, so that when the last contact 6 is reached, only the sliding arm 11keeps contact 6 electrically connected to capacitor 20, whereas whensliding arm 12 arrives at contact 6, no such electric connection ismaintained with capacitor 21.

The apparatus of FIG. 1 functions as follows: Assuming that the slidingarm 11 is upon the first contact 4 of the series, when theshutter-release key is depressed so as to close the battery switch 34,the capacitor 20 will become charged in the shortest possible timeacross resistor 3'. This time constant corresponds to the shortestpossible closing time of the shutter, e.g. l/2000 second. If the slidingarm 11 is moved toward the position shown in FIG. 1, the RC timeconstant becomes progressively longer and so does the shutter closingtime. Besides the normal exposure times, intermediate values can be set.When the sliding arm 11 has arrived at contact 6 the sliding arm 12arrives at the first contact 4. The capacitor 21 is of such a size thattogether with the first partial resistor of the stepped rheostat 2, anRC member will be formed whose time constant will correspond to that ofthe sum of the partial resistors of the stepped rheostat 2 and capacitor20, thereby permitting the exposure time to be increased to about l/25second. In actual practice when the sliding arm 12 moves upon firstcontact 4, only the capacitor 21 will be charged. By the making of sucha contact a certain timing error may be introduced so that the angles a,and or; do not need to be exact and continuous contact maintained toobtain satisfactory functioning of the timer, as during motorizedactuation. If now the rotatable setter is turned further, the slidingarm 11 will be moved beyond its operative range and the charging of theRC member will be across the sliding arm 12 and the relatively largercapacitor 21 will become charged and the relatively longer exposuretimes from 1/8 to 1/16 second retained.

As has been mentioned before it is the purpose of the present timingselector to provide a certain voltage at the terminals 22 at certainpreestablished time periods (shutter time) after actuation of theshutter-release key. The voltage ob tained from the terminals issupplied to an electronic shutter control device known per se whichcauses the shutter to be closed whenever this certain voltage isreached. It should particularly be noted that the opening of the shutteris performed purely mechanically be pressing the shutter-release key,and only the closing of the shutter is achieved by means of theelectronic control device.

Having this in mind it will be apparent that special means must beprovided for shutter closing after a so called B exposure, this beingthe exposure whereby the shutter is opened upon pressing of the shutterrelease key, where it stays open as long as the key remains depressed,and where it is closed upon removing the finger from the key, i.e. uponrelease of the key.

The means provided for performing this function comprise a furthercontact 31 being arranged at the end of the rheostat and being connectedby way of a resistor 30 directly to the battery 1. Associated withcontact 31 is a sliding point 32 which is connected by a switch 33 tothe low-capacitance capacitor 20. Contact 31 and sliding point 32 aredisposed relative to one another in such a way that upon setting thetimer to the B setting sliding arm 11 establishes an electricallyconductive connection between the contact and the sliding point. By thisconnection capacitor 20 is in effect connected to battery 1 and wouldbecome charged if switch 34 would be closed. The latter, however,remains open until the shutterrelease key is pressed. Then switch 34 isactually closed, since switch 34 is mechanically connected to theshutter-release key so as to be closed when the key is actuated and tobe opened when the key is released, as has been mentioned before.

Upon actuation of the shutter-release key capacitor 20 would actuallybecome charged, were it not for switch 33 which is also mechanicallycoupled to the shutter-release key so as to be opened'upon keyactuation, which switch opening occurs just prior to the closing ofswitch 34. Thus, even if the shutter-release key is pressed capacitor 20is still not charged because switch 33 has been opened. And it is notuntil the shutter-release key is released that also switch 33 is closedwhile switch 34 is still closed, as a consequence whereof capacitor 20is now charged in a very short time, thus providing the necessaryvoltage at the terminals 22 for the closing of the shutter.

The working phases of the switches 33, 34 during shutter key actuationbeing thus: shutter key pressing: first switch 33 is opened, then switch34 is closed, shutter key release: first switch 33 is closed, thenswitch 34 is opened, and thereafter switch 33 is also opened. In theoverlapping period of time when both shutters are closed capacitor 20 ischarged within fractions of a second. The mechanical coupling of theswitches 33, 34 to the shutterrelease key need not further be describedsince it is considered a matter of simple design which is within theknowledge of anyone skilled in this type of design work.

FIGS. 2 and 3 show a modification of the timer on an enlarged scale. Itconsists of two platelike ring discs 7 and 8 and the rotatable setter 10with its arms 11 and 12 whose free ends are bifurcated. The sliding arms11, 12 comprise two electrically connected fingers 15, 16 and 17, 18which are arranged in spaced apart planes. The ring disc 8 carries onone side of it an electric resistance layer from which resistors 3 areformed, and on its other side the contacts 4, 5 and 6 which areelectrically connected with the resistance layer 3 by rivets 9. Theplate 7 has the slideways 13 and 14 mounted on the inner side of it.Fingers 15 and 16 are electrically connected to each other. The slidingcontact surface of finger 16 is wide enough to bridge over the spacebetween successive contacts 4 and 6.

In FIG. 3 the paths 13 and 14 of the contact arms and the rotatablesetter 10 are indicated in dot and dash lines. The time setter has apotentiometer 40 built into it and coupled to it to compensate for filmsensitivity and diaphragm setting for determining the exposure time.

The fingers of sliding arms 11 and 12 are provided with cooperatingknobs so that one arm will be in engagement with contacts 4, 5 orslideways 13, 14, while the other arm is out of engagement therewith,and that in the transitional range at contact 6, both arms will be inengagement with these parts.

We claim:

1. A timing setter for cameras having an electronic timing circuitcontaining an RC member which includes a stepped rheostat and amechanically movable timing setter for setting the time constant, theimprovement comprising:

a. a plurality of contacts (4,5,6) on said rheostat;

b. a first capacitor (20) having a given capacitance contained in saidRC member;

c. a second capacitor (21) having a greater capacitance than said givencapacitance contained in said RC member; and

d. said timing setter having a plurality of sliding arms (11,12) thefirst of which is electrically connected with said first capacitor andthe second of which is connected with said second capacitor, said firstand second sliding arms spaced from one another and having successivebridging connection with said contacts and a transitional range whereinthe time constant of the first sliding arm is about the same as that ofsaid second sliding arm while said capacitors are uncoupled from oneanother.

2. The timing setter of claim 1, wherein said contacts of the rheostatare arranged along an arch whose subtended angle a, is less than andsaid spaced first and second sliding arms define an internally subtendedangle a, which is smaller than said an le 3. T e timing setter of claim2, further comprising a first slideway (13) on said rheostat connectingwith said first sliding arm (11) and a second slideway (14) on saidrheostat connecting with said second sliding arm (12), the slidewaysbeing of different angular extents.

4. The timing setter of claim 3, wherein said sliding arms (11,12)comprise two electrically connected fingers (15,16,17,18) arranged inspaced apart planes and said contacts (4,5,6) and said slideways (13,14)are arranged in similarly superimposed planes.

5. The timing setter of claim 3, wherein said first sliding path (13) isconnected with said first capacitor (20) and said second sliding path(14) is connected with said second capacitor (21) and said firstslideway is longer than said second slideway.

6. The timing setter of claim 5, wherein said sliding arms aresufficiently broad to bridge successive contacts whereby the rheostat isstepped and the RC member provides means for giving a shutterintermediate closing times in addition to normal gradations.

7. The timing setter of claim 6 in combination with a camera having a Bsetting, and further comprising electric means in the circuit of thelow-capacitance capacitor (20), said means being deenergized uponactuation of said shutter actuator and being energized upon release ofsaid shutter actuator for charging said capacitor in a short period oftime after shutter actuator release.

8. The timing setter of claim 7, wherein said means comprise a contact(31) in addition to said contacts of the stepped rheostat, said contact(31) being electrically connected to the battery (1) by way ofa resistor(30), a sliding point (32) being arranged adjacent to said contact (31),said sliding point being electrically connected to said capacitor (20),and said contact and said sliding point being electrically connected bysaid first sliding arm (11) when said timing setter (10) is set to saidB setting, and a normally closed switch (33) between said sliding point(32) and said capacitor (20), said switch being mechanically connectedto said shutter operator so as to be opened upon actuation of saidshutter operator prior to closing of the battery switch (34).

1. A timing setter for cameras having an electronic timing circuitcontaining an RC member which includes a stepped rheostat and amechanically movable timing setter for setting the time constant, theimprovement comprising: a. a plurality of contacts (4,5,6) on saidrheostat; b. a first capacitor (20) having a given capacitance containedin said RC member; c. a second capacitor (21) having a greatercapacitance than said given capacitance contained in said RC member; andd. said timing setter having a plurality of sliding arms (11,12) thefirst of which is electrically connected with said first capacitor andthe second of which is connected with said second capacitor, said firstand second sliding arms spaced from one another and having successivebridging connection with said contacts and a transitional range whereinthe time constant of the first sliding arm is about the same as that ofsaid second sliding arm while said capacitors are uncoupled from oneanother.
 2. The timing setter of claim 1, wherein said contacts of therheostat are arranged along an arch whose subtended angle Alpha 1 isless than 180* and said spaced first and second sliding arms define aninternally subtended angle Alpha 2 which is smaller than said angleAlpha
 1. 3. The timing setter of claim 2, further comprising a firstslideway (13) on said rheostat connecting with said first sliding arm(11) and a second slideway (14) on said rheostat connecting with saidsecond sliding arm (12), the slideways being of different angularextents.
 4. The timing setter of claim 3, wherein said sliding arms (11,12) comprise two electrically connected fingers (15,16,17,18) arrangedin spaced apart planes and said contacts (4,5,6) and said slideways(13,14) are arranged in similarly superimposed planes.
 5. The timingsetter of claim 3, wherein said first sliding path (13) is connectedwith said first capacitor (20) and said second sliding path (14) isconnected with said second capacitor (21) and said first slideway islonger than said second slideway.
 6. The timing setter of claim 5,wherein said sliding arms are sufficiently broad to bridge successivecontacts whereby the rheostat is stepped and the RC member providesmeans for giving a shutter intermediate closing times in addition tonormal gradations.
 7. The timing setter of claim 6 in combination with acamera having a B setting, and further comprising electric means in thecircuit of the low-capacitance capacitor (20), said means beingdeenergized upon actuation of said shutter actuator and being energizedupon release of said shutter actuator for charging said capacitor in ashort period of time after shutter actuator release.
 8. The timingsetter of claim 7, wherein said means comprise a contact (31) inaddition to said contacts of the stepped rheostat, said contact (31)being electrically connected to the battery (1) by way of a resistor(30), a sliding point (32) being arranged adjacent to said contact (31),said sliding point being electrically connected to said capacitor (20),and said contact and said sliding point being electrically connected bysaid first sliding arm (11) when said timing setter (10) is set to saidB setting, and a normally closed switch (33) between said sliding point(32) and said capacitor (20), said switch being mechanically connectedto said shutter operator so as to be opened upon actuation of saidshutter operator prior to closing of the battery switch (34).